This invention relates to polymeric materials based on 5-t-butylisophthalic acid which are melt-processable and, more particularly, to polyaramide and polyarylate polymers and copolymers based on a compound containing the 5-t-butylisophthaloyl moiety and partially or wholly aromatic diamines or diols, which polymers and copolymers have the excellent thermal and mechanical properties of polymeric materials of these structure types and also, because of their amorphous nature and substantial processing temperature window, can be melt-processed into various shaped article forms such as fibers, films, coatings and molded objects.
Among the most important synthetic polymers are polyesters and polyamides. These polymers exhibit a wide range of desirable chemical and physical properties. Within these two broad categories are (1) polyarylates, polyesters made using aromatic diacids and aromatic diols or their derivatives, and (2) polyaramides, polyamides made from aromatic diacids and aromatic diamines or their derivatives. Both of these classes of polymers are considered engineering polymers. In the case of polyaramides, which generally have superior thermal and other physical properties, for example, Nomex and Kevlar, the polymers are not commercially melt-processable and often are only soluble in corrosive solvents such as sulfuric acid, from which fibers may be spun. Many polyaramides also have extremely high softening points, often above 400.degree. C., and are thermally unstable in the melt. Some polymers and copolymers of these two classes incorporating the diacyl functionality of 5-t-butylisophthalic acid or its derivatives are reported in the patent literature. Now it has been found that by combining a monomer containing the 5-t-butylisophthaloyl moiety, alone or in combination with other diacyl moieties, with a wholly or partially aromatic diamine or diol monomer, amorphous polyaramides or polyarylates which have a substantial processing temperature window are produced. Such a finding can lead to less expensive fibers, films, coatings and molded objects which have the same or better physical properties than, e.g., Nomex, a commercial polymer made from isophthalic acid and m-phenylenediamine which is not commercially melt-processable.
An extensive patent literature exists for polyaramides and polyarylates, including those which contain the t-butylisophthaloyl moiety. In U.S. Pat. Nos. 2,715,620 and 2,794,794, a compound containing the 5-t-butylisophthaloyl moiety is used with aliphatic diamines and diols of between 5 and 10 carbon atoms to make polyamides and polyesters with improved heat resistance as compared to polymers made using the isophthaloyl moiety. Wholly aromatic polyamides are taught by Hill in U.S. Pat. No. 3,094,511 and Kwolek in U.S. Pat. No. 3,063,966, and the list of useful aromatic diacids includes lower alkyl 5-substituted isophthalic acids and diamines such as m- and p-phenylenediamines. In U.S. Pat. No. 3,408,334, Example 13 teaches a polyaramide made from the 5-t-butylisophthaloyl moiety and 4,4'-oxybisaniline which is said to be useful as a fiber. Hanson et al. in U.S. Pat. No. 4,042,750 teach polyamides and shaped articles made from the polyamides. Example III of that patent discloses the formation of a polyaramide made from 5-t-butyl-isophthalic acid and methylenebisaniline.
Polyarylates and copolyarylates made from a large number of aromatic diacids and aromatic diols including the 5-t-butylisophthaloyl moiety and bisphenol A are taught in, e.g., U.S. Pat. Nos. 3,546,165, 3,684,766 and 4,102,864.